Sinusitis is a condition affecting over 35 million Americans, and similarly large populations in the rest of the developed world. Sinusitis occurs when one or more of the four paired sinus cavities (i.e., maxillary, ethmoid, frontal, sphenoid) becomes obstructed, or otherwise has compromised drainage. Normally the sinus cavities, each of which are lined by mucosa, produce mucous which is then moved by beating cilia from the sinus cavity out to the nasal cavity and down the throat. The combined sinuses produce approximately one liter of mucous daily, so the effective transport of this mucous is important to sinus health.
Each sinus cavity has a drainage pathway or outflow tract opening into the nasal passage. This drainage passageway can include an ostium, as well as a “transition space” in the region of the ostia, such as the “frontal recess,” in the case of the frontal sinus, or an “ethmoidal infundibulum,” in the case of the maxillary sinus. When the mucosa of one or more of the ostia or regions near the ostia become inflamed, the egress of mucous is interrupted, setting the stage for an infection and/or inflammation of the sinus cavity, i.e., sinusitis. Though many instances of sinusitis may be treatable with appropriate medicates, in some cases sinusitis persists for months or more, a condition called chronic sinusitis, and may not respond to medical therapy. Some patients are also prone to multiple episodes of sinusitis in a given period of time, a condition called recurrent sinusitis.
Balloon dilation has been applied to treat constricted sinus passageways for the treatment of sinusitis. These balloon dilation devices typically involve the use of an inflatable balloon located at the distal end of a catheter such as a balloon catheter. Generally, the inflatable balloon is inserted into the constricted sinus passageway in a deflated state. The balloon is then expanded to open or reduce the degree of constriction in the sinus passageway being treated to facilitate better sinus drainage and ventilation. At the same time most, if not all, of the functional mucosal tissue lining of the sinuses and their drainage passageways are preserved.
Exemplary devices and methods particularly suited for the dilation of anatomic structures associated with the maxillary and anterior ethmoid sinuses are disclosed, for example, in U.S. Pat. No. 7,520,876 and U.S. Patent Application Publication No. 2008-0172033. Other systems have been described for the treatment of various other sinuses including the frontal sinus. For example, U.S. Patent Application Publication No. 2008-0097295 discloses a frontal sinus guide catheter (FIG. 6B) and method of treating the frontal sinuses (e.g., FIGS. 8B-8C). U.S. Patent Application Publication No. 2008-0125626 discloses another guide device (e.g., FIGS. 10C and 10C′) for transnasal access to the frontal sinuses for treatment.